Shadowing issue with sunken areas on landscape

Having a problem with getting the lights to “light” the bottom of the depressed areas in the landscape.
Tried turning on Static Shadow & Far Shadow

Any ideas?

Is there some sort of a water plane on those areas? Also have you tried increasing the lightmap resolution of the landscape to see if that helps?

Thanks for replying. Yeah I tried to increase the static light resolution to 3 with no improvement.